Double-phase high-entropy porous alloy electrode material for direct seawater electrolysis as well as preparation method and application of double-phase high-entropy porous alloy electrode material

Abstract

The invention discloses a double-phase high-entropy porous alloy electrode material for direct seawater electrolysis and a preparation method and application thereof, a precursor of the electrode material is an A-B double-component alloy, a component A of the precursor comprises three or more of active elements Fe, Co, Ni, Cu, Mn, Cr and Zn, and a component B of the precursor comprises one or more of second-phase forming elements Al, V and Mo. Through selective phase corrosion-electrochemical activation, an A dynamic active sacrificial phase / B steady state inert matrix phase synergistic system is constructed: the A dynamic active sacrificial phase is a relatively active FCC phase in a precursor, and the A dynamic active sacrificial phase can be leached / oxidized to form an oxyhydroxide active layer and construct an anion barrier layer; the latter phase is a BCC phase or a sigma phase and can be used as a self-supporting framework to provide Cl-corrosion resistance and structural stability. The material has a three-dimensional bicontinuous graded porous characteristic, and the catalytic activity and the corrosion-resistant stability are both considered in direct seawater electrolysis. The preparation process depends on smelting forming, electrochemical selective corrosion and electrochemical activation, the process is short, and large-scale production can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis hydrogen production technology, specifically relating to a two-phase high-entropy porous alloy electrode material for direct seawater electrolysis, as well as the preparation method of the material and its application in alkaline seawater electrolysis hydrogen production. Background Technology

[0002] With increasing global dependence on fossil fuels and rapid population growth, the environmental crisis continues to escalate, seriously threatening global sustainable development. Among various emerging clean energy carriers, green hydrogen (H2) has become one of the core energy carriers driving the low-carbon transition due to its high energy density and carbon-free operation. Utilizing renewable energy sources (such as solar, wind, and tidal energy) to drive water electrolysis for hydrogen production is an important component of the future energy system.

[0003] However, traditional water electrolysis for hydrogen production is highly dependent on ultrapure freshwater as a raw material. Global freshwater resources are scarce and unevenly distributed, severely restricting the large-scale and global development of water electrolysis for hydrogen production. Against this backdrop, seawater electrolysis for hydrogen production, which accounts for approximately 96.5% of the Earth's total water resources and can be integrated with offshore renewable energy systems (offshore wind, tidal, and photovoltaic systems), has become a key direction for overcoming resource bottlenecks.

[0004] Currently, seawater electrolysis for hydrogen production mainly follows two technical paths:

[0005] One technological approach is indirect seawater electrolysis (ISE): seawater is first converted into freshwater through desalination processes (such as reverse osmosis or distillation), and then hydrogen is produced by electrolysis. Although this technology is relatively mature, the seawater desalination process consumes a lot of energy and costs, and the system integration is low, making it difficult to achieve low-cost, large-scale application.

[0006] Another technological approach is direct seawater electrolysis (DSE): seawater is directly electrolyzed after only simple pretreatment (such as filtering impurities), without the need for a separate desalination process. This approach is expected to significantly reduce costs, improve system scalability and integration flexibility, and is an ideal development direction for seawater electrolysis hydrogen production.

[0007] However, direct seawater electrolysis technology faces a core challenge: corrosion caused by Cl-, which is a key bottleneck restricting its industrialization. During direct seawater electrolysis, high concentrations of Cl- in seawater compete with oxygen evolution reaction (OER) intermediates for active sites, triggering a side reaction—chlorine evolution reaction (ClOR). This not only reduces electrolysis efficiency but also poisons catalytic active sites, accelerates electrode structure degradation, and leads to rapid decline in electrode performance. Therefore, developing Cl- resistant, low-cost, and highly active non-precious metal catalysts is a core requirement for promoting the industrialization and commercialization of direct seawater electrolysis, and has significant practical implications for promoting hydrogen energy development and utilization and alleviating the energy crisis.

[0008] Currently, the technological challenges in the field of direct seawater electrolysis are mainly reflected in two aspects: strategies for resisting Cl- corrosion and electrode preparation methods.

[0009] (a) Limitations of existing Cl- corrosion resistant strategies

[0010] 1. Anion barrier layer strategy: By leaching and oxidizing lattice elements of the catalyst, an accumulation layer of oxygen-containing anions or hydroxylated species is formed at the electrode interface, using electrostatic repulsion to keep Cl- ions away from the active sites. However, this strategy has a fatal flaw—continuous leaching of lattice elements accelerates the destruction of the overall lattice structure of the catalyst, and bubble impacts during electrolysis cause fluctuations in the barrier layer, requiring continuous consumption of lattice elements to maintain the integrity of the barrier layer, making the catalyst unable to adapt to long-term continuous electrolysis;

[0011] 2. Ion-selective coating strategy: An ultrathin ion-selective coating is constructed on the catalyst surface to physically block Cl- from contacting the active sites while allowing OER reactants (H2O, OH-) to diffuse. However, the protective effect of the coating depends entirely on its structural integrity: under industrial-grade high current densities, the coating is prone to local defects, and Cl- can quickly penetrate and cause electrode corrosion; in addition, the process requirements for preparing dense, defect-free coatings are stringent, making large-scale mass production difficult.

[0012] (II) Shortcomings of existing electrode fabrication methods

[0013] 1. Binder Coating Method: Nanoparticle catalytic active materials are coated onto the substrate surface using a binder. In this method, the binder covers part of the active sites, hindering the contact between the electrolyte and the active sites, while increasing the electron transport resistance and reducing catalytic performance. Furthermore, the coated catalyst film has weak adhesion to the substrate and is prone to detachment under high current densities in industrial applications. In addition, the binder itself is easily attacked and deactivated by Cl-, leading to the pulverization of the catalyst film.

[0014] 2. Chemical growth method: Catalysts are grown on foamed metal substrates using chemical methods such as hydrothermal deposition and electrodeposition. This method is energy-intensive and easily generates harmful pollutants during preparation, which does not conform to the concept of green manufacturing. At the same time, the controllability of the product structure is poor, making it difficult to meet the requirements of electrode consistency for industrial applications.

[0015] Seawater electrolysis for hydrogen production offers advantages in terms of resources and system integration. However, direct seawater electrolysis (DSE) is significantly affected by Cl- corrosion and chlorine evolution side reactions. Existing barrier layer / selective coating and binder coating / chemical growth methods have limitations in terms of industrial current density, long-term stability, and scalable manufacturability. Therefore, there is an urgent need for materials and processes that combine high activity, Cl- corrosion resistance, self-support, and mass production capabilities.

[0016] To address the aforementioned problems in existing technologies, we propose a two-phase high-entropy porous alloy electrode material for direct seawater electrolysis, its preparation method, and its application. Summary of the Invention

[0017] The purpose of this invention is to solve the problem that it is difficult to balance the activity and stability of electrode materials in direct seawater electrolysis and that traditional processes are difficult to mass-produce. The invention proposes a solution that is achieved by combining a two-phase structure induced by the second phase formation element with a simplified process chain.

[0018] To achieve the above objectives, the present invention provides the following technical solution: a two-phase high-entropy porous alloy electrode material for direct seawater electrolysis, wherein the electrode material comprises a two-phase alloy formed of AB components.

[0019] The active elements of the matrix phase in component A include three or more of Fe, Co, Ni, Cu, Mn, Cr, and Zn, which are mixed to form the FCC phase;

[0020] The second phase forming elements of component B include one or more of Al, V, and Mo, and the above elements are mixed to form the BCC phase or σ phase.

[0021] The FCC phase, BCC phase, and σ phase are all high-entropy alloy phases;

[0022] The BCC phase or σ phase constitutes the ligament matrix of the material, the surface of the FCC phase forms micron pores with a diameter of 0.05 to 0.4 μm, and the surface of the FCC phase is distributed with nanopores with a diameter of 1 to 20 nm. The electrode material as a whole constitutes a three-dimensional double continuous hierarchical porous structure.

[0023] The electrode material also has a hydroxyl oxide active layer on its surface.

[0024] Furthermore, the total content of active elements in the matrix phase is 75-88%; the total content of second phase forming elements is 12-25%.

[0025] Another object of the present invention is to provide a method for preparing the above-mentioned dual-phase high-entropy porous alloy electrode material for direct seawater electrolysis.

[0026] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a two-phase high-entropy porous alloy electrode material for direct seawater electrolysis, comprising the following steps:

[0027] S1. Preparation of dual-phase precursor alloy: After cleaning all the metal raw materials, they are melted by electric arc under an inert atmosphere according to the proportion. The melting and cooling are repeated to obtain a dual-phase precursor alloy block containing both FCC phase and BCC phase / σ phase.

[0028] S2. Molding: The dual-phase precursor alloy block is formed into strips or plates;

[0029] S3. Selective phase corrosion to create pores: Place the above strips or plates in the electrolyte, set the corrosion voltage to the inflection point of the curve ±0.5V according to the Tafel curve, and set the corrosion time to the characteristic peak value of the curve ±500s according to the chronocurrent curve, so as to selectively remove the surface FCC phase and retain the BCC / σ phase to obtain a three-dimensional double continuous porous structure.

[0030] S4. Surface activation: The above materials are electrochemically activated in an alkaline electrolyte to form a hydroxyl oxide active layer on the material surface, thus obtaining a biphase high-entropy porous alloy electrode material.

[0031] Furthermore, in S2, the strip is obtained by single-roll quenching, with the quenching copper roller rotating at a speed of 1000-2000 r / min, the strip thickness being 40-100 μm, the width being 20-100 mm, and the thickness deviation being ≤5 μm.

[0032] Furthermore, in S2, a sheet material with a thickness of 0.2 to 0.6 mm is obtained by cold rolling or hot rolling.

[0033] Furthermore, in S3, the electrolyte is selected as a 1 mol / L (NH4)2SO4 solution, and the electrolyte temperature is 25-40℃; the corrosion process adopts a three-electrode system: the working electrode is the strip or plate, the counter electrode is graphite, and the reference electrode is Ag / AgCl.

[0034] Furthermore, the alkaline electrolyte in S4 is selected as 1M KOH or 1M KOH+0.5M NaCl; the activation process adopts cyclic voltammetry with a voltage window of 0.2-0.6V, a scan rate of 10-100mV / s, and 200-500 scans.

[0035] Another object of the present invention is to provide an electrode for direct seawater electrolysis, said electrode being made of the material described in claim 1 or 2, and the electrode being a self-supporting structure that does not require a binder.

[0036] Another objective of this invention is the application of the above-mentioned electrode in the electrolysis of water to produce hydrogen in an alkaline seawater electrolyzer.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) Dual-phase synergy: This invention induces the formation of a dual-phase FCC (face-centered cubic) + BCC / σ (body-centered cubic / orthorhombic) structure through a second-phase element, and selectively removes the surface portion of the FCC phase in S3, combined with in-situ activation in S4 to generate an active layer, achieving a balance between high activity and corrosion resistance. The electrode material surface consists of a dual-phase functional system composed of a dynamically active sacrificial phase and a stable inert matrix phase.

[0039] Dynamic active sacrificial phase: originating from the relatively active FCC phase in the precursor. During selective corrosion and electrochemical activation, the FCC phase is preferentially corroded first, forming a hierarchical porous structure (micron-pores and nanopores), which significantly increases the electrochemical active area; at the same time, its surface is further transformed into a hydroxyl oxide active layer (such as NiOOH, CoOOH), which replenishes a large number of active sites;

[0040] Steady-state inert matrix phase: Composed of BCC or σ phase, it provides resistance to Cl- corrosion and three-dimensional framework support, ensuring long-term stability of the material structure.

[0041] (2) Mass transfer and bubble management: The three-dimensional bicontinuous “micron-nano” pore structure makes electrolyte mass transfer and bubble desorption smoother, reducing the probability of ClOR.

[0042] (3) Simplified process and large scale: The short process of electric arc melting + spin quenching / rolling + electrochemical corrosion + activation, relying on mature equipment, can mass-produce self-supporting electrodes and avoid the problems of shielding and failure caused by binders.

[0043] (4) Adjustable composition: By adjusting the A / B element and content window, the pore structure, biphase ratio and active layer composition can be directionally adjusted to adapt to different seawater salinity and working conditions. For example, increasing the Al element content can expand the micron pore diameter and improve mass transfer efficiency; increasing the Mo element content can improve corrosion resistance by constructing a denser anion barrier layer.

[0044] (5) Excellent electrochemical performance: When used as an anode in alkaline seawater electrolysis, after long-term continuous electrolysis, its surface morphology remains smooth, without cracks, pulverization, or other signs of failure, with minimal mass loss and good electrode structural integrity. These properties demonstrate that the material of this invention can operate stably for a long time in high current density and Cl-containing electrolysis environments, providing reliable material support for the industrialization of direct seawater electrolysis for hydrogen production. At 100 mA·cm⁻¹ - The overpotential of OER is low at 1000 mA·cm. - 2. Achieve long-term stable operation under industrial-grade current density. Attached Figure Description

[0045] Figure 1 This is a flowchart of the preparation process of the present invention;

[0046] Figure 2 This is a scanning electron microscope (SEM) image of the dual-phase high-entropy porous alloy electrode material prepared in Example 1 of this invention.

[0047] Figure 3 The X-ray diffraction pattern of the dual-phase high-entropy porous alloy electrode material prepared in Example 1 of this invention;

[0048] Figure 4This is a scanning electron microscope (SEM) image of the dual-phase high-entropy porous alloy electrode material prepared in Example 3 of this invention.

[0049] Figure 5 The X-ray diffraction pattern of the dual-phase high-entropy porous alloy electrode material prepared in Example 3 of this invention;

[0050] Figure 6 This is a scanning electron microscope image of the single-phase high-entropy alloy material prepared in Comparative Example 2 of this invention.

[0051] Figure 7 The X-ray diffraction pattern of the single-phase high-entropy alloy material prepared in Comparative Example 2 of this invention;

[0052] Figure 8 The image shows the scanning electron microscope morphology of the dual-phase high-entropy alloy material prepared in Comparative Example 3 of this invention before the activation step.

[0053] Figure 9 Linear scan voltammetry plots comparing the seawater electrolysis OER activity performance of Example 1 of the present invention with that of Comparative Examples 1, 2, and 3;

[0054] Figure 10 This is a chronovoltaic graph comparing the stability performance of direct seawater electrolysis in Example 2 and Comparative Example 1 of the present invention.

[0055] Figure 11 This is a chronovoltaic graph comparing the stability performance of alkaline simulated seawater electrolysis under industrial current conditions in Example 2 and Comparative Example 1 of the present invention.

[0056] Figure 12 This is a schematic diagram of the mechanism of the dual-phase high-entropy porous alloy electrode material designed for this invention. Detailed Implementation

[0057] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. The embodiments and comparative examples are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods; the materials, reagents, instruments, etc., used are commercially available unless otherwise specified. Unless otherwise stated, all percentages are atomic percentages (at.%), and mass fractions are indicated according to the context; all electrochemical tests were performed at room temperature (25±2℃), and the electrode geometry was calibrated to 1 cm². 2 .

[0058] Example 1: Component A is Ni-Co-Fe-Cr, and component B is Al.

[0059] The preparation steps of a two-phase high-entropy porous alloy electrode material for direct seawater electrolysis are as follows:

[0060] (1) Preparation of precursor alloys

[0061] Weigh out high-purity metal raw materials (purity ≥ 99.9%), including Ni, Co, Fe, Cr, and Al, according to the nominal composition Ni. 30 Co 30 Fe 10 Cr 10 Al 20 The total mass of the mixture is 40g. The metal raw material consists of cylindrical particles with a diameter of 2mm and a height of 4mm. Before use, each metal particle is sequentially placed in ultrapure water and anhydrous alcohol for ultrasonic cleaning, each cleaning lasting 10-15 minutes, for a total of 3 cycles. After cleaning, the particles are dried with a hair dryer to prevent residual liquid from causing metal oxidation.

[0062] The cleaned raw material was placed in a crucible of a vacuum arc furnace, and 40g of Ti was placed in another crucible for oxygen absorption. The process was continued until the vacuum level in the chamber reached 2×10⁻⁶. -4 After Pa, the alloy is subjected to arc melting, and then repeatedly melted 3-5 times under electromagnetic stirring to ensure uniformity. After cooling, a large, regularly shaped dual-phase precursor alloy is obtained.

[0063] (2) Alloy strip forming

[0064] The precursor alloy is cut into small pieces and placed in a single-roller quenching system. Under the protection of an argon atmosphere, it is melted into a liquid alloy and sprayed out through a quartz nozzle with a diameter of 1.5 mm and a spray pressure of about 1.5 atm. It is sprayed onto the surface of a water-cooled copper roller rotating at 1400 rpm and rapidly cooled to obtain an alloy strip with a thickness of about 45 μm and a width of 5 mm, with a thickness deviation of less than 5 μm.

[0065] (3) Electrochemical selective phase corrosion pore formation

[0066] The strip was cut into 10mm × 5mm pieces to serve as the working electrode, a graphite rod as the counter electrode, and an Ag / AgCl electrode as the reference electrode, constructing a three-electrode system. The electrolyte was a 1M (NH4)2SO4 solution (25℃). The Tafel curve of the sample was obtained using linear sweep voltammetry. The inflection point corresponded to the corrosion potential difference between the FCC and BCC phases, and the corrosion voltage was set near the inflection point. Selective corrosion was performed using chronoamperometry. When the current-time curve showed a characteristic peak, the corrosion time was controlled before and after the peak. After corrosion treatment, the surface layer of the FCC phase was selectively removed, while the inert BCC or σ phase remained uncorroded, forming a biphase high-entropy alloy electrode material with a micron-nano hierarchical porous structure.

[0067] (4) Electrochemical activation to construct the active layer

[0068] The porous strip was used as the working electrode, the graphite rod as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte was either 1M KOH or 1M KOH + 0.5M NaCl solution. Cyclic voltammetry (CV) was used to activate the electrode, with a voltage window of 0.2-0.6V (vs. Hg / HgO), a scan rate of 100mV / s, and 200 scans. During activation, a stable hydroxyl oxide active layer (such as NiOOH or CoOOH) was formed on the material surface.

[0069] (5) Performance Testing

[0070] The aforementioned dual-phase high-entropy porous alloy material was directly applied to the anode for alkaline seawater electrolysis hydrogen production. The test conditions were either actual seawater or simulated seawater (1M KOH + 0.5M NaCl). Results showed that at a current density of 100 mA / cm², [the anode was successfully applied]. 2 Under the same conditions, the OER overpotential is approximately 310 mV, which is significantly better than that of the Ni mesh electrode (overpotential approximately 561 mV).

[0071] Figure 2 The image shows a SEM image of the biphase high-entropy porous alloy electrode material prepared in Example 1. The image reveals a typical biphase porous structure. Based on this structure, a dense hydroxyl oxide film further covers its surface. This film effectively seals the nanoscale pores but does not completely block the connectivity of the micrometer-scale channels. Combined with… Figure 3 The XRD analysis results show that the dual-phase high-entropy porous alloy electrode material prepared in Example 1 is composed of two phases, FCC and BCC.

[0072] This embodiment illustrates the mechanism of selective phase corrosion in a dual-phase alloy (composed of an FCC phase and a BCC / α phase): Under the action of the corrosive medium, the electrochemical stability of different crystal structures varies, with the FCC phase exhibiting higher corrosion sensitivity and thus preferentially dissolving in the early stages of corrosion. Specifically, the approximately 10-100 nm thick layer on the surface of the FCC phase undergoes preferential corrosion, resulting in an overall surface depression; while the adjacent BCC phase remains relatively stable and is almost uncorroded, thus retaining its original height. As a result, a micron-scale pore structure is formed near the phase interface, enclosed by the depressed FCC phase region and the uncorroded BCC phase region. In addition to this scale effect, further corrosion of the FCC phase surface also generates localized nanoscale corrosion pits, exhibiting multi-order-of-magnitude pore structure characteristics on the FCC grain surface. Thus, a multi-scale, multi-level pore structure is formed on the material surface, with micron-scale pores and nanoscale pits superimposed on each other. Therefore, selective phase corrosion can be used to control the micro- and nano-structures on the surface of materials based on the electrochemical inhomogeneity of two-phase alloys, thereby constructing materials with special functions (such as enhanced catalytic activity or increased specific surface area).

[0073] Example 2: Component A is Ni-Co-Fe-Cr, and component B is Al-Mo.

[0074] The preparation process is the same as in Example 1, except that step (1) includes Ni, Co, Fe, Cr, Al, and Mo, according to the nominal composition Ni 30 Co 30 Fe 10 Cr 10 Al 18 Mo2 ratio.

[0075] The introduction of Mo enhances the stability of the BCC phase and modulates corrosion kinetics, resulting in a more uniform pore structure distribution and better mechanical stability. Simultaneously, Mo-O species form during corrosion, improving chlorine resistance and intrinsic electrocatalytic activity. Experimental results show that its OER activity and stability are superior to those of Example 1.

[0076] Example 3: Component A is Mn-Co-Fe-Ni, and component B is V.

[0077] The preparation process is the same as in Example 1, except that step (1) includes Mn, Ni, Co, Fe, and V, according to the nominal composition Mn 50 Ni 12.5 Co 12.5 Fe 12.5 V 12.5 Proportioning.

[0078] Figure 4 The image shows a SEM image of the biphase high-entropy porous alloy electrode material prepared in Example 3. The surface also has a biphase porous structure, with a hydroxyl oxide layer grown in its micron-sized pores. Figure 5 The XRD pattern shows that the phase structure of the biphase high-entropy porous alloy electrode material prepared in Example 3 consists of FCC and σ phase.

[0079] The high Mn content makes it prone to forming the corrosion-sensitive FCC phase, while V is stably present in the BCC phase and provides a supporting framework after corrosion. Corrosion results in a hierarchical structure with higher porosity, significantly increasing the specific surface area. MnO is formed under alkaline conditions. x The MnOOH species enhances the active sites, but because the conductivity of Mn is lower than that of Ni and Co, the overall conductivity of the system is weak.

[0080] Example 1 achieves a good balance between pore structure and conductivity; Example 2, due to the introduction of Mo, exhibits the best performance in terms of corrosion resistance, conductivity and structural stability; Example 3, although lacking in conductivity, is suitable for applications requiring a large number of active sites due to its high porosity and the formation of surface active species.

[0081] Comparative Example 1: Commercial Ni mesh

[0082] A comparison of the performance of a commercial Ni mesh with that of Example 1 of the present invention shows that the commercial Ni mesh has a single FCC phase structure. Due to the lack of selective corrosion effect induced by the biphase structure and the micron-nano hierarchical pore structure, its electrochemical activity is significantly inferior to that of the present invention.

[0083] Comparative Example 2: Component A is Ni-Co-Fe-Cr, and component B is Al.

[0084] The preparation process is the same as in Example 1, except that step (1) includes Ni, Co, Fe, Cr, and Al, according to the nominal composition Ni. 40 Co 30 Fe 10 Cr 10 Al 10 Proportioning.

[0085] Figure 6 The SEM results of the electrode material prepared for Comparative Example 2 show that it does not form a hierarchical porous structure of "micrometer + nanometer," but rather a uniformly distributed layer of hydroxyl oxides. Combined with... Figure 7 The XRD results show that Comparative Example 2 is a single FCC phase. Due to the lack of a second phase, the corrosion process is carried out uniformly in the single phase, and therefore a hierarchical pore structure cannot be formed.

[0086] Compared with the performance of Example 1 of this invention, the alloy contains only 10 at.%, which is insufficient to stably induce the formation of the second phase, BCC, and the overall structure remains a single FCC structure. During electrochemical corrosion, the lack of interphase potential difference results in localized pitting or shallow corrosion pits, failing to form a hierarchical porous structure, and its performance is significantly lower than that of Example 1. This is because elements such as Ni, Co, and Fe tend to stabilize the FCC phase, while elements such as Al are conducive to the formation of a stable BCC phase. Only when the Al content reaches a certain proportion can phase separation be driven to form an FCC+BCC dual-phase structure, thereby utilizing the preferential dissolution of the FCC phase and the relative stability of the BCC phase to construct micron-nano-level pores during selective corrosion. When the Al content is insufficient, the second phase cannot be formed, thus losing the conditions for synergistic dual-phase corrosion.

[0087] Comparative Example 3: Component A is Ni-Co-Fe-Cr, and component B is...

[0088] The alloy system has the same composition as in Example 1, but without surface activation (step S4).

[0089] Figure 8The image shows a SEM image of the electrode material prepared in Comparative Example 3. This sample did not undergo the S4 activation step, therefore no hydroxyl oxide active layer was formed on the surface. The two phases can be directly distinguished in the SEM image: the phase with a smooth surface and no corrosion marks is the BCC phase, while the phase with a surface full of nanopores is the FCC phase, which is consistent with the porous structure model proposed in this invention.

[0090] Due to the lack of a hydroxyl oxide active layer (such as NiOOH, CoOOH), the surface active sites are insufficient, resulting in the electrode's activity in the OER reaction being inferior to that in Example 1.

[0091] Please refer to Table 1 for a comparison of the structure and electrochemical activity of the electrode materials prepared in the above embodiments and comparative examples.

[0092] Table 1 Comparison of structural performance of each embodiment and comparative example

[0093]

[0094] Figure 9 The chart shows a comparison of the LSV performance of Example 1 with Comparative Examples 1, 2, and 3 in an alkaline simulated seawater solution. The results show that Example 1 exhibits the best electrochemical activity. This is mainly due to the hierarchical porous framework formed by its two-phase corrosion, which significantly increases the electrochemical active area, while the activation process generates a large amount of hydroxyl oxide active material on the surface. In contrast, Comparative Example 1 (commercial Ni mesh) has much lower activity; Comparative Example 2 (single-phase alloy), although activated to generate hydroxyl oxides, has limited active area due to the lack of hierarchical channels; Comparative Example 3 (two-phase alloy but not activated), although having a large specific surface area, did not generate active material on its surface, and its activity was also inferior to Example 1. In summary, the superior performance of Example 1 stems from the synergistic effect of the hierarchical porous structure formed by selective corrosion of the two-phase structure and the high-density surface-active material generated during the activation process.

[0095] Figure 10 The results of Example 2 and Comparative Example 1 in an alkaline seawater solution at 100 mA·cm⁻¹ are shown. - Stability comparison under 2 conditions. The results show that Comparative Example 1 (commercial Ni mesh) can only operate stably for less than 10 hours, while Example 2 can maintain stable electrolysis for up to 980 hours. This is because the unique two-phase structure of Example 2 endows the material with excellent corrosion resistance, in which the BCC phase acts as a stable inert framework, effectively maintaining the long-term stability of the overall structure.

[0096] Figure 11 Further comparisons were made between Example 2 and Comparative Example 1 under industrial current density conditions (1000 mA·cm). -2Stability under conditions of 6500 hours of electrolysis. During this process, Example 2 maintained small voltage fluctuations and a potential difference of approximately 0.5V compared to Comparative Example 1, indicating that it not only possesses excellent catalytic activity but also outstanding long-term stability.

[0097] Figure 12 This diagram illustrates the mechanism of action of a dual-phase high-entropy porous alloy electrode material. The core mechanism lies in the preferential corrosion of the FCC phase on the surface, forming a micron- and nano-level hierarchical pore structure, thereby significantly increasing the number of electrochemically active sites. Based on this, electrochemical activation generates a hydroxyl oxide layer (such as NiOOH or CoOOH) on the surface, providing active catalytic sites. Simultaneously, the BCC or σ phase, as a stable inert matrix phase, provides resistance to Cl- corrosion and a three-dimensional self-supporting framework, ensuring the long-term integrity of the overall structure. The synergistic effect of the two phases significantly enhances the electrochemical activity and durability of the material.

[0098] In summary, this invention achieves a balance between high activity and high stability through the synergistic effect of a biphase structure design and an activation process. Without departing from the basic principles and spirit of this invention, those skilled in the art can still make various changes, modifications, and substitutions to its embodiments, all of which should be covered within the scope of protection of the appended claims and their equivalents.

Claims

1. A dual-phase high-entropy porous alloy electrode material for direct seawater electrolysis, characterized in that: The electrode material comprises a dual-phase alloy formed by AB dual components, The active element of the A-component base phase includes three or more of Fe, Co, Ni, Cu, Mn, Cr, and Zn, which are mixed to form an FCC phase; The second-phase forming element of the B-component includes one or more of Al, V, and Mo, which are mixed to form a BCC phase or a σ phase; The FCC phase, the BCC phase, and the σ phase are all high-entropy alloy phases; The BCC phase or the σ phase constitutes a material ligament matrix, the FCC phase surface layer forms micropores with a diameter of 0.05-0.4 μm, and the FCC phase surface is distributed with nanopores with a diameter of 1-20 nm, and the electrode material as a whole constitutes a three-dimensional dual-continuous hierarchical porous structure; The electrode material surface also has a hydroxyl oxide active layer.

2. The dual-phase high-entropy porous alloy electrode material for direct seawater electrolysis according to claim 1, characterized in that: The total content of the active element of the base phase is 75-88%, and the total content of the second-phase forming element is 12-25%.

3. A method for preparing a dual-phase high-entropy porous alloy electrode material for direct seawater electrolysis according to claim 1 or 2, characterized in that: The method comprises the following steps, S1. Preparation of a dual-phase precursor alloy: after cleaning all the metal raw materials, the raw materials are arc melted in an inert atmosphere according to the ratio, repeatedly melted and cooled to obtain a dual-phase precursor alloy block containing an FCC phase and a BCC phase / σ phase; S2. Forming: the dual-phase precursor alloy block is made into a strip or a plate; S3. Selective phase corrosion pore forming: the strip or the plate is placed in an electrolyte, the corrosion voltage is set to the inflection point value of the Tafel curve ± 0.5 V, and the corrosion time is set to the characteristic vertex value of the chronoamperometry curve ± 500 s, so as to selectively remove the surface FCC phase and retain the BCC / σ phase, thereby obtaining a three-dimensional dual-continuous porous structure; S4. Surface activation: the material is electrochemically activated in an alkaline electrolyte to form a hydroxyl oxide active layer on the surface of the material, thereby obtaining a dual-phase high-entropy porous alloy electrode material.

4. The method for preparing dual-phase high-entropy porous alloy electrode materials for direct seawater electrolysis according to claim 3, characterized in that: In S2, the strip is prepared by single-roller spin casting, the spin casting copper roller rotates at a speed of 1000-2000 r / min, the thickness of the strip is 40-100 μm, the width is 20-100 mm, and the thickness deviation is ≤5 μm.

5. The method for preparing dual-phase high-entropy porous alloy electrode materials for direct seawater electrolysis according to claim 3, characterized in that: In S2, the plate with a thickness of 0.2-0.6 mm is prepared by cold rolling or hot rolling.

6. The method for preparing dual-phase high-entropy porous alloy electrode materials for direct seawater electrolysis according to claim 3, characterized in that: In S3, the electrolyte is selected to be a 1 mol / L (NH4)2SO4 solution, and the electrolyte temperature is 25-40°C; the corrosion process adopts a three-electrode system: the working electrode is the strip or the plate, the counter electrode is graphite, and the reference electrode is Ag / AgCl.

7. The method for preparing dual-phase high-entropy porous alloy electrode materials for direct seawater electrolysis according to claim 3, characterized in that: In S4, the alkaline electrolyte is selected to be 1M KOH or 1M KOH+0.5M NaCl; the activation process adopts cyclic voltammetry, the voltage window is 0.2-0.6 V, the scanning rate is 10-100 mV / s, and the scanning is 200-500 times.

8. An electrode for direct seawater electrolysis, characterized by The electrode is made of the material of claim 1 or 2, and the electrode is a self-supporting structure without binder.

9. Application of the electrode of claim 8 in hydrogen production by electrolysis of water in an alkaline seawater electrolysis cell.

Images